RFR: 8178352: BitMap::get_next_zero_offset may give wrong result on Mac

[Stefan Karlsson]

Hi Kim,

On 2017-04-10 00:00, Kim Barrett wrote:
> Please review this change to BitMap::get_next_zero_offset_inline to
> remove its use of left_n_bits, thereby avoiding
> https://bugs.openjdk.java.net/browse/JDK-8178348.
>
> CR:
> https://bugs.openjdk.java.net/browse/JDK-8178352
>
> Webrev:
> http://cr.openjdk.java.net/~kbarrett/8178352/hotspot.00/


The bug fix looks good.

You did a couple of stylistic changes that now make the code inconsistent:

-    for (; res & 1; res_offset++) {
-      res = res >> 1;

+    for (; (res & 1) == 0; ++res_offset) {
+      res >>= 1;


But the surrounding code uses this format:
  271     for (; !(res & 1); res_offset++) {
  272       res = res >> 1;
  273     }

I think these changes should be kept out of this patch.

Thanks,
StefanK

>
> Testing:
> JPRT, with the test from
> https://bugs.openjdk.java.net/browse/JDK-8169039
> included in the tested repository.
>